The overall objective of this research is to understand the role that human female reproductive tract (FRT) epithelial cells play in innate immune protection against HIV-1. As sentinels of innate immune defense, epithelial cells throughout the reproductive tract are the first line of protection against sexually transmitted infections and are crucial for orchestrating a rapid response to potential viral pathogens. Our goal in this proposal is to test the hypothesis that epithelial cells from White-American, African- American, and Tanzanian women exhibit intracellular and secreted antiviral activity that protects the reproductive tract against HIV-1. The specific aims of the current research project are to answer the following questions: 1) To what extent do epithelial cell secretions protect the female reproductive tract from HIV-1 ? 2) Do intracellular antiviral factors inhibit HIV-1 replication? 3) To what extent do candidate topical microbicides affect epithelial cell innate defenses? 4) Do epithelial cells influence the risk of HIV-1 infection of T cells and macrophages in the underlying stromal FRT? 5) Do FRT epithelial cells from Tanzanian women exhibit secreted and/or intracellular mechanisms of protection against HIV-1? We plan to investigate these questions using human primary epithelial cells from throughout the female reproductive tract and reproductive tract cell lines, since these cells are infectable by HIV-1, capable of protecting against HIV-1 infection, and responsive to sex hormones. The research described in this proposal will further our understanding of the mucosal immune responses involved in defending against HIV-1 and should lead to the identification of ways to augment protective responses. These studies should provide the basis of knowledge essential for the development of more effective microbicides, therapeutic interventions,